There is a substantial Chechen exile community in Turkey, which is particularly strong in Istanbul, and millions of Turks also trace their ancestry to the Caucasus.

During the Russian military campaigns against Chechen rebels in the last few years, there have been persistent allegations from Russia that Turkish organisations have offered financial and material support to the independence movement.

In 1996 pro-Chechen gunmen seized a ferry

The Turkish and Russian governments recently signed an agreement for closer co-operation against militant groups, and the authorities in Ankara have always insisted that there is no official support for the rebel campaign.

But Chechen fighters have been treated in Turkish hospitals, and the ruthlessness of the Russian military has generated considerable sympathy among ordinary Turks for their Chechen brethren.

Turkey has also been dragged unwillingly into several previous hijackings involving the Chechen issue.

The most famous occurred in 1996, when a group of pro-Chechen gunmen seized control of a passenger ferry off Turkey's northern Black Sea coast.

More than 200 people were held hostage for several days by a gang, which included both Chechens and Turks.

The hijackers were eventually imprisoned but all of them later escaped amid strong suspicions that they were allowed to go free.